Both start-ups and established companies have increasingly launched digital business models in recent years. Some of them focus on the business-to-business (B2B) sector and follow the business model of an electronic marketplace (EM). B2B electronic marketplaces are functioning as internet platforms bringing together demand and supply which is why they are often called matchmakers. According to the existing e-commerce and EM literature, the model of an EM is particularly attractive for fragmented markets, with many small and medium-sized suppliers. The argument behind this is that an electronic marketplace can significantly reduce search and transaction costs for the buyers’ side due to the aggregation of numerous suppliers. There are many highly fragmented B2B markets, in which such an aggregation via a platform could add value. But less is known about the early validation of a marketplace business model. The case of a venture called Coating Radar shows this validation process based on the concept of a minimum viable product and the lean start-up approach. This represents a contribution to the still young research field of digital entrepreneurship. Furthermore, it turns out that the product-market-fit is negative for the Coating Radar. From this result, a potential generalization could be that fragmented B2B markets might be attractive for new marketplace business models. But only a systematic validation can show whether a platform business idea can become a sustainable business. This complements the literature in the field of electronic marketplaces and B2B e-commerce.